Electrical connectors are used in many different types of electrical and electronic systems. They come in various sizes depending on the physical and electrical parameters of the installation. Some high-speed digital signal applications require multiple contact connectors in a single rectangular module that are held together and are stackable without distorting or adversely modifying the signal integrity. Digital signals must have a high degree of signal integrity on entering and exiting an electrical connector system. Requirements for connector types, in increasingly high-speed applications include a high degree of shielding, preventing signal distortion from outside Electromagnetic Interference (EMI), and low inductance and resistance for signal and return signal paths.
Rectangular connectors with multiple contacts are two millimeter (2 mm) or less in center spacing have limits in contact density and signal shielding by currently employed manufacturing processes. However, electronic systems that use high-speed connectors continue to shrink in physical size and require increasing signal density, which requires reducing the physical size requirements for connectors. Present rectangular connectors having a plurality of contacts have limits in providing dense signal packaging and shielding of each individual contact within the connector-housing module. This is because the typical contact is not shielded along the contact length as in classical coaxial connectors.
Although classical round coaxial connectors have contiguous shielding along their contact length and provide low inductance and good signal integrity, they do not offer a large number of contacts, particularly for densities of 2 mm on-center or less in a rectangular configuration. In round coaxial connections, multiple contiguous contacts cannot be densely packed or stacked in a module form to densities attainable in a rectangular configuration and still have each signal contact surrounded within a metal enclosure along the length of the contact. Rectangular connectors for high-speed digital signal applications that employ a plurality of contacts with 2 mm on-center or less spacing use a combination of injection molded plastics and metal. In particular, the plastic parts are either riveted or press-fitted to metal plates to simulate shielding, to form signal impedance matching, and to reduce inductance and resistance in order to improve signal integrity. However, these connector systems, while providing greater contact densities than round coaxial connectors, do not provide a contiguous metal cavity along the length of each individual contact. Instead, only one or two sides of each individual contact has a shield.
Presently, most high-density connectors are either electrical or optical. Some fiber optic interfaces occur at the printed circuit board level and are designed to convert the electrical signal to light (optical) signals. These interfaces typically include one or more small electrical-to-optical devices, such as vertical cavity surface emitting lasers (VCSELs). These devices, along with some signal-conditioning electronics (e.g, a bias-T) are adapted to receive electrical high-speed signals and convert them into high-speed modulated light signals. How ver, tere are signal density issues with the present state-of-the art connectors. Accordingly, there is a need for a truly hybrid connector, i.e., a connector that can provide connectivity for a variety of different types of electrical signals, or electrical and optical signals.